The instant invention relates to the general problem of service location in wide area computer networks and, more particularly, to the specific problem which arises when a user wishes to locate some service, such as a media bridge, internet telephony gateway, H.323 Gatekeeper, unicast to multicast bridge, etc., which has some desired characteristics, but whose location (in terms of network address, domain or geographical location) is completely unknown and may be anywhere on the public network.
Today, there exists a number of examples of wide area services. One is media bridges, which are devices used for mixing voice or video together for multipoint conferences. Another might be a media server, which contains movies and multimedia accessible to the user for playback. Another example are Internet telephone gateways. These devices allow Internet hosts to communicate with standard xe2x80x9cPOTSxe2x80x9d telephone users by translating Internet telephony to traditional telephony. Yet another example is a multicast to unicast bridge, which would allow unicast-only endpoints to receive multicast.
Generally, with currently existing technology, service location mechanisms need to be involved for every call set-up. This makes their location a time critical, and potentially network and CPU intensive operation. Furthermore, relaying internet telephony calls to the PSTN results in cost for the gateway provider which must somehow be passed on to the remote user. This also requires security mechanisms to provide authentification and authenticity in an international environment.
Prior art systems and devices exist for locating services, but none work well for wide area network service location. For example, some prior art publications have taught the use of DNS records for finding services in a particular domain. See for example A. Gulbrandsen, P. Vixie, xe2x80x9cA DNS RR for Specifying the Location of Services (DNS SR V)xe2x80x9d, IETF Request for Comments 2052, October 1996, and R. Moats, M. Hamilton, P. Leach, xe2x80x9cFinding Stuffxe2x80x9d, IETF InternetDraft draft-ietf-srvloc-discovery-02.txt, Work in progress. Prior art publications have also addressed the problem of finding fax gateways in a particular telephone exchange; see, for example, C. Malamud, M. Rose, xe2x80x9cPrinciples of Operation for TPC.INT Subdomain: General Principles and Policyxe2x80x9d, IETF Request for Comments 1530, October 1993.
The use of DNS requires the client to know the domain name where the server is located, which is generally not possible. The Service Location Protocol, see for example, J. Veizades, E. Guttman, C. Perkins, S. Kaplan, xe2x80x9cService Location Protocolxe2x80x9d, IETF Request for Comments 2165, June 1997, is used for location of services in an administrative domain, but does not work for wide area networks as it ends up using excessive bandwidth as more servers and clients use it. The Session Announcement Protocol (SAP), M. Handley, xe2x80x9cSAP - Session Announcement Protocolxe2x80x9d, EETF Internet Draft, Work in Progress, allows for announcement of services, but requires an excessive amount of time for clients to learn about them. Web search engines, such as Lycos and Alta Vista, can also be used for the location of services. However, such search engines tend to generate excessive traffic, and service location control rests in the hands of a few, dedicated search facilities. This has limited scalability.
It is, therefore, an object of the instant invention to provide a solution to the service location problem which is efficient and scalable both in use of bandwidth and CPU power.
It is a further object of the instant invention to provide a protocol architecture which allows clients in a data network to readily locate services in a wide area network.
It is another object of the instant invention to provide a protocol architecture which scales to an infinite number of clients and millions of servers without requiring excessive bandwidths, while at the same time being fast, simple and flexible.
The claimed invention comprises a protocol architecture which allows clients connected to a data network to locate services in a wide area network such as the internet. The invention scales to an infinite number of clients and millions of servers without requiring excessive bandwidths and is also fast, simple and flexible.
The inventive method includes activating a server X to provide a service A to clients and when activated server X multicasts an advertisement for service A to a multicast group G1.
Broker Y stores the advertisement for service A in its database and multicast the advertisement for service A to a multicast group G2, which advertisement is detected by Directory Agent Z and stored in Z""s data base.
A client, looking to find a server for service A queries Directory Agent Z and receives the address for Broker Y, who then provides to the client the address for server X.
The client is then able to contact server X to obtain service A.